Explosive western US wildfire 20 percent contained

GROVELAND, California (AP) — The giant wildfire burning at the edge of Yosemite National Park is 20 percent contained, U.S. fire officials said.

The fire had burned through 280 square miles (725 sq. kilometers) in northern California, destroyed 111 structures and threatened water supplies, hydroelectric power and giant sequoia trees — a state icon — as of late Tuesday. Some 4,500 structures remained threatened.

The fire, one of the largest in state history, has caused air pollution problems in California cities far from the scene.

Forestry experts said unnaturally long intervals between wildfires and years of drought primed the Sierra Nevada mountains for the explosive fire in the rugged landscape.

Federal forest ecologists said historic policies of fire suppression to protect timber interests left a century’s worth of fuel in the fire’s path.

Two years of drought and a constant slow warming across the Sierra Nevada also worked to turn the Rim Fire into an inferno.

For years, forest ecologists have warned that Western wildfires will only get worse.